package org.apache.lucene.document;

/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * A {@link FieldSelector} based on a Map of field names to
 * {@link FieldSelectorResult}s
 * 
 */
public class MapFieldSelector implements FieldSelector {

	private static final long serialVersionUID = -3525236528425245086L;
	Map<String, FieldSelectorResult> fieldSelections;

	/**
	 * Create a a MapFieldSelector
	 * 
	 * @param fieldSelections
	 *            maps from field names (String) to {@link FieldSelectorResult}s
	 */
	public MapFieldSelector(Map<String, FieldSelectorResult> fieldSelections) {
		this.fieldSelections = fieldSelections;
	}

	/**
	 * Create a a MapFieldSelector
	 * 
	 * @param fields
	 *            fields to LOAD. List of Strings. All other fields are NO_LOAD.
	 */
	public MapFieldSelector(List<String> fields) {
		fieldSelections = new HashMap<String, FieldSelectorResult>(fields
				.size() * 5 / 3);
		for (final String field : fields)
			fieldSelections.put(field, FieldSelectorResult.LOAD);
	}

	/**
	 * Create a a MapFieldSelector
	 * 
	 * @param fields
	 *            fields to LOAD. All other fields are NO_LOAD.
	 */
	public MapFieldSelector(String... fields) {
		this(Arrays.asList(fields));
	}

	/**
	 * Load field according to its associated value in fieldSelections
	 * 
	 * @param field
	 *            a field name
	 * @return the fieldSelections value that field maps to or NO_LOAD if none.
	 */
	public FieldSelectorResult accept(String field) {
		FieldSelectorResult selection = fieldSelections.get(field);
		return selection != null ? selection : FieldSelectorResult.NO_LOAD;
	}

}
